Exposure to coarse particles (PM10-2.5) was associated with right-ventricular effects in the heart of susceptible participants in the Multi-Ethnic Study of Atherosclerosis. Right-ventricular dysfunction (and enlargement) is a common sequela of chronic respiratory disease. This analysis was based on 5-year exposures calculated through land-use regression models, and magnetic resonance images from 1,490 adult participants. An increase in 2.2 mg/m3 was associated with a 0.5 g larger right-ventricular mass among former smokers; a 0.9 g mass increase among current smokers; and a 1.4 g increase among people with emphysema. No associations were found for healthy individuals, nor for other measures of right-ventricular function. The findings suggest that alterations of the heart structure may be one of the mechanisms involved in the cardiovascular effects of coarse particles for susceptible people.